Google Calendar - Spend less time managing your day & more time enjoying it
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Jorte - Schedule books must be practical and has a good design.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.